The present invention relates to heat exchange devices, self-cooling electronic systems using same, and methods for cooling electronic devices using the same. More particularly, the present invention relates to forged, finned-tube heat exchangers and cold plates, self-cooled electronic devices using finned-tube heat exchangers to cool and support the electronic devices, and to methods for controlling the operating temperature of small, high-density, high power electronic devices using finned-tube heat exchangers.
Thermal control of powerful electronic components is of paramount importance with systems and devices using those electronic components. Indeed, the increasingly smaller size of the electronic components advantageously enables higher density applications, which allows designers to produce smaller and smaller products. However, higher density applications produce more heat in smaller areas. Accordingly, in order to maintain the electronic components and the system itself within operable temperatures, heat removal from the heat-producing electronic components is essential.
Heat removal by thermal conduction is one means of transferring heat produced by high-power devices to ambient air. Conventional devices for conductive heat removal include heat sinks, heat exchangers, cold plates, and the like. Typically, the power device to be cooled is structured and arranged in direct or indirect thermal contact with the heat sink, heat exchanger, cold plate, and the like. The heat sink, heat exchanger, cold plate, and the like typically are fabricated of a material with high thermal conductivity to draw heat from the power device and transfer it to ambient air.
The amount of heat removed by conduction is directly proportional to the contact area between the heat source and the heat sink, heat exchanger, cold plate, and the like; the thermal conductivity of the heat sink, heat exchanger, cold plate, and the like; and the surface area of the heat sink, heat exchanger, cold plate, and the like exposed to ambient air. Thus, to enhance thermal conduction, it is not uncommon to include a plurality, or, more preferably, a multiplicity of pins or fins that extend substantially vertically from a surface of the heat sink, heat exchanger, cold plate and the like. The vertically-extending pins or fins provide additional surface area to enhance heat removal.
Alternatively or additionally, heat removal can include convection. Convection involves heat removal by the circulation of one or more fluids, e.g., air, gas, vapor, water, oil, coolant, water ethylglycol (WEG), and the like, around, through, and/or against the device, heat sink, heat exchanger, cold plate, and the like. The circulating fluid draws heat from the device, heat sink, heat exchanger, cold plate, and the like, and transports the heat to ambient air.
The amount of heat removed by convection is directly proportional to the thermal conductivity of the cooling fluid, the fluid flow rate, the size of the flow channel, and the exposed surface area past which the cooling fluid can flow. Moreover, the type of fluid flow, i.e., laminar or turbulent, can impact heat removal. For example, turbulent flow provides greater heat removal potential than laminar; however, improved heat removal comes at a price of greater pressure drops. Those skilled in the art appreciate the delicate balance that must be drawn between the type of fluid flow and the pressure loss associated with that flow in designing a convection heat sink, heat exchanger, cold plate, and the like.
Problems with the prior art include the dichotomy of making electronic components smaller and smaller, which requires heat sinks, heat exchangers, cold plates, and the like with larger surface areas to remove more heat from the electronic components. Furthermore, the heat sinks, heat exchangers, cold plates and the like of the prior art rarely provide any other function besides heat removal. For example, heat sinks, heat exchangers, cold plates, and the like have not been used to remove heat and to provide structural support to electronic components. Accordingly, there is a need for a lightweight, compact heat removing device that also can provide structural support to electronic components.
The present invention provides a lightweight, compact heat exchanger and/or cold plate for cooling or thermally controlling high-density electronic devices. The present invention further provides a self-cooling electronic component system using the compact heat exchanger and/or cold plate and a method for cooling or thermally controlling high-density electronic devices using the heat exchanger and/or cold plate.
According to one embodiment of the present invention, a heat exchanger comprises a metal tube that has been forged and drawn to form a heat exchanger and/or cold plate for cooling or thermally controlling heat-producing electronic components. According to one aspect of the present invention, the metal tube is a thick-walled tube that is forged into suitable geometries for cooling electronic devices. Preferably, forging maintains a tube wall thickness that will enable the tube to be used to support one or more heat-producing electronic components structurally. The metal tube includes an inner surface and an outer surface. The outer surface provides sufficient surface area to attach and to support one or more heat-producing electronic components. The inner surface provides an enclosed flow channel through which a fluid, e.g., air, gas, vapor, water, oil, coolant, WEG, and the like, circulates to remove heat by convection.
The inner surface of the metal tube includes a plurality of integral fins that are structured and arranged to enhance heat transfer from the metal tube to the circulating fluid. Preferably, the integral fins disposed on the inner surface of the tube have a pitch and a height-to-width ratio that optimizes the total surface area that is exposed to the cooling fluid. Moreover, the fin width, pitch, length, aspect ratio, twist angle, and disposition with respect to other integral fins can be controlled to optimize heat removal and thermal requirements and to minimize pressure drops through the metal tube. The variability of the fin structure and arrangement enables tailoring the metal tube for a myriad of uses.
Preferably, the geometry of the metal tubes exhibits a substantially rectangular or flattened round shape with a cross-sectional aspect ratio (width to depth) that ranges between about 1 to 1 to about 20 to 1. More preferably, the cross-sectional aspect ratio is at least about 4 to 1 and no more than about 5 to 1.
In a second embodiment, the present invention comprises a self-cooling, self-supporting electronic assembly that comprising:
one or more high-power electronic devices;
a heat exchange device that is in thermal communication with the one or more high-power electronic devices to support and remove heat therefrom; and
an attaching system to which said one or more high-power electronic devices are releasably attached and said heat exchange device is coupled to provide rigidity, structure, and strength to the electronic assembly.
In yet another embodiment, the present invention provides a method of cooling an electronic component, the method comprising the steps of:
providing a heat exchange device that is in direct thermal communication with said one or more heat producing means, wherein the heat exchange device comprises a tube having an inner surface and an outer surface, wherein the outer surface is in thermal communication with the one or more heat-producing devices and the inner surface defines a flow channel for a cooling fluid, wherein said inner surface includes a plurality of integral fins that are structured and arranged about the flow channel to optimize heat transfer from said inner surface and said plurality of integral fins to the cooling fluid; and
circulating a fluid through said heat exchange device to conduct heat away from said heat exchange device and said one or more heat producing assemblies.